Risk factors for iliopsoas impingement after total hip arthroplasty using a collared femoral prosthesis

Does Lack of Initial Collar-Calcar Contact Influence Performance of Collared Cementless Femoral Stems?

Background

Initial stability of cementless stems is important to minimize the risk of subsidence, pain, and periprosthetic fracture after total hip arthroplasty (THA). Collared stems improve initial component stability when contacting the femoral calcar. Direct contact is not always achieved, and collared stem performance has not been studied in this context. We hypothesized that collared stems achieving direct contact would demonstrate reduced subsidence.

Methods

A single-surgeon retrospective study of 482 consecutive primary THAs implanted between February 2020 and May 2023 using collared cementless stems was performed. The 2 cohorts included stems with initial collar-calcar contact vs stems without. Subsidence was evaluated by comparing intraoperative fluoroscopy to postoperative 8-week radiographs. Binary logistic regression identified independent risk factors for subsidence. Chi-square tests were used for categorical variables and t-tests for continuous variables.

Results

Of stems, 63.9% achieved initial collar-calcar contact, while 36.1% did not. The rate (1.3% vs 19.0%; P < .001) and magnitude (0.02 mm, range 0-3 mm vs 0.35 mm, range 0-3 mm; P < .001) of subsidence were significantly higher among stems without initial contact. Stems without initial collar-calcar contact (P < .001) and male gender (P = .007) were independent risk factors for subsidence. Two patients with initial contact had nondisplaced calcar cracks and <3 mm of subsidence at 4 weeks, which healed with protected weight-bearing. Stem survivorship was 100% in both groups, with all achieving osteointegration and none needing revision.

Conclusions

Excellent performance of collared cementless stems was observed at 8 weeks after primary THA. Initial collar-calcar contact lowered the risk and magnitude of minor subsidence but did not affect survivorship or fracture risk.

Level of Evidence

Level III.

Increased hip flexion angle and protrusion of the anterior acetabular component can predict symptomatic iliopsoas impingement after total hip arthroplasty: a retrospective study

BACKGROUND

Iliopsoas impingement (IPI) is a known complication of total hip arthroplasty (THA). The aim of this study was to identify risk factors and the cut-off cup protrusion length for symptomatic IPI.

METHODS

We retrospectively reviewed 218 hips (46 men, 172 women) of 190 consecutive Japanese patients who underwent primary THA at our institution. Hips with IPI (n = 24) and control hips (n = 194) were compared according to age, body mass index, and clinical scores. We evaluated leg-length discrepancy, global offset, implant alignment angles, pelvic inclination, and anterior cup protrusion on plain radiographs and computed tomography scans.

RESULTS

Symptomatic IPI had an incidence of 11.0% and a predilection for hips with osteonecrosis. Pre- and postoperative hip flexion angles were significantly greater in hips with symptomatic IPI (p = 0.013 and p = 0.006, respectively). Cup protrusion length was significantly greater in hips with IPI (4.7 mm vs. 1.4 mm; p = 0.001). Receiver-operating characteristic curve analysis identified a threshold cup protrusion length of 3.9 mm (sensitivity 0.89, specificity 0.63) for symptomatic IPI. The incidence of symptomatic IPI tended to be lower in patients with greater posterior pelvic sagittal inclination despite the cup protrusion length being greater.

CONCLUSIONS

An increased hip flexion angle and protrusion of the anterior acetabular component predicted symptomatic IPI. The threshold cup protrusion length suggesting mild IPI might be about 3.9 mm and could be useful for identifying candidates for conservative treatment.

Relationship between iliopsoas muscle surface pressure and implant alignment after total hip arthroplasty: a cadaveric study

Iliopsoas impingement after total hip arthroplasty is caused by the implant irritating the iliopsoas muscle, but changes in the iliopsoas muscle have not been quantitatively evaluated. This study assessed changes in the surface pressure of the iliopsoas muscle when the implant alignment was varied. Total hip arthroplasty was performed in 10 fresh-frozen cadaveric hips. We evaluated the maximum and mean surface pressure of the iliopsoas muscle with the hip in 20° and 10° extension, the neutral position, and 10° flexion when the anterior cup protrusion length (ACPL), stem version, and stem offset were varied. When the ACPL was changed to 0, 3, and 6 mm in 20° extension, the maximum surface pressure was significantly increased for ACPL of 6 mm compared with 0 mm. Decreased stem anteversion resulted in a significant reduction in both the maximum and mean surface pressure compared with native anteversion from 20° extension to the neutral position. Increased stem offset resulted in significant increases in the maximum and mean surface pressure of the iliopsoas muscle compared with decreased stem offset in 20° extension. Not only large ACPL but also changes in stem version and offset affected the maximum surface pressure of the iliopsoas muscle.

Incidence and Risk Factors of Iliopsoas Tendinopathy After Total Hip Arthroplasty: A Radiographic Analysis of 1,602 Hips

BACKGROUND

Iliopsoas tendinopathy (IPT) can cause persistent groin pain and lead to dissatisfaction after total hip arthroplasty (THA). This study aimed to report the characteristics, incidences, risk factors, and treatment outcomes of IPT after THA.

METHODS

We reviewed primary THAs performed at a single institution between January 2012 and May 2018. Clinical and radiographic analyses were performed on 1,602 THAs (1,370 patients). Patient characteristics, component sizes, inclination and anteversion angles, and antero-inferior cup prominence (≥8 millimeters (mm)), were compared between the groups with and without IPT. Changes in teardrop to lesser trochanter distance were measured to estimate changes in leg length and horizontal offset caused by THA. Logistic regression models were used to identify the risk factors for IPT. IPT was identified in 53 hips (3.3%).

RESULTS

Patients with IPT had greater leg lengthening (12.3 versus 9.3 mm; P = .001) and higher prevalence of antero-inferior cup prominence (5.7 versus 0.4%; P = .002). There was no significant difference in inclination, anteversion, and horizontal offset change between the two groups. In multivariate analyses, greater leg lengthening, prominent acetabular cup, women, and higher body mass index were associated with IPT. All patients reported improvement in groin pain after arthroscopic tenotomy, while 35.7% with nonoperative management reported improvement (P < .001).

CONCLUSIONS

Symptomatic IPT occurred in 53 (3.3%) of the 1,602 primary THAs. Our findings suggest that leg lengthening as well as prominent acetabular cup in THAs can be associated with the development of IPT. Arthroscopic tenotomy was effective in relieving groin pain caused by IPT.

Editorial Commentary: The Cause of Groin Pain Is Difficult to Determine: The Elusive "Nether-Nether Region"

As one of the many causes of groin pain, iliopsoas tendinitis can be hard to identify and even harder to treat. It occurs in the setting of both the native hip joint and following total hip arthroplasty. Internal snapping, or coxa saltans, can result from the iliopsoas snapping over the anterior hip capsule or iliopectineal eminence and can be a source of labral pathology. The snapping can be painful or painless. Iliopsoas impingement over total hip components either from the cup or collar of a femoral stem are causes of anterior groin pain. However, there are multiple other causes of groin pain, both intra- and extra-articular, that can make finding the source of the pain difficult. Referred pain from the spine, gynecologic, and gastrointestinal systems can all cause pain in the groin. Core muscle injuries and athletic pubalgia can all cause groin pain and frequently mimic intra-articular hip pathology or iliopsoas tendinopathy. Ultrasound-guided diagnostic injection into the iliopsoas bursa or the juxtaposed hip joint (intra-articular injection) can be helpful in differentiating the source of the pain. Combining a clear history, detailed physical, basic and advanced imaging, as well as diagnostic injection is essential in diagnosing this elusive entity and guiding appropriate treatment.

Survival analysis for all-cause revision following primary total hip arthroplasty with a medial collared, triple-tapered primary hip stem versus other implants in real-world settings

OBJECTIVE

Patients that undergo total hip replacement (THA) are at risk of revision surgery. This study evaluated the cumulative incidence of revision following a medial collared, triple tapered (MCTT) primary hip stem versus other implants in real-world settings using electronic medical records.

METHODS

This was a retrospective cohort study that used the Mercy Healthcare Systems - Orthopedics Database (MHSOD) to identify ACTIS total hip system, a MCTT primary hip stem for THA, and any other primary THA between 2016 and 2020. A Kaplan-Meier analysis was conducted to evaluate the risk of revision over time between the MCTT hip stem and other implants. In order to control for the confounding, a multivariable Cox model was developed to evaluate the risk of revision between the two groups.

RESULTS

There were 1213 patients treated with MCTT hip stem and 6916 patients treated with other implants. The Kaplan-Meier analysis showed statistically significant difference (p value = .006) in cumulative incidences for all-cause revisions between the MCTT hip stem and other implants. The cumulative incidence at 3 years was 1.08% (0.43-2.72%) for the MCTT hip stem, while it was 2.63% (2.19-3.16%) for other implants. After adjusting for patient demographics, clinical characteristics, prescribed medications, and surgeon characteristics, the multivariable Cox proportional hazard model showed the MCTT hip stem was statistically significantly associated with 57% lower risk of revisions compared with other implants (HR, 0.43; 95% CI, 0.19-0.97; p-value = .042).

CONCLUSIONS

This real-world study found that the incidence of revision after treatment with MCTT primary hip stem was significantly lower than for other implants.